JP3569795B2 - Fluid bed incinerator - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fluidized bed incinerator for incinerating municipal solid waste and industrial waste.
[0002]
In this specification, the left side of FIGS. 1 to 4 is referred to as front, the opposite side is referred to as rear, the upper side of FIGS. 2 to 4 is referred to as left, and the opposite side is referred to as right.
[0003]
[Prior art]
As a fluidized bed incinerator of this type, the present applicant firstly formed a fluidized bed by flowing a fluidized medium in the lower part of a vertical cylindrical furnace body, where a primary combustion chamber for burning incinerated material was provided. A secondary combustion chamber is provided at an upper part of the furnace body for burning unburned components and pyrolysis gas by secondary combustion air blown into the combustion gas, and a secondary combustion chamber is provided between the primary combustion chamber and the secondary combustion chamber. A throttle portion having a substantially rectangular horizontal cross section is provided, and one first nozzle for blowing secondary combustion air in a direction orthogonal to a long side direction of the throttle portion is provided at an upper end portion of the primary combustion chamber. In addition, a fluidized bed incinerator has been proposed in which a plurality of second nozzles for blowing out secondary combustion air in the lateral direction are provided on the walls of two long sides of the narrowed portion so as to face each other. See Heihei 8-61636).
[0004]
[Problems to be solved by the invention]
However, according to the results of observation of the combustion state in the furnace with an industrial television camera and the temperature distribution in the furnace obtained from the analysis based on the temperature measurement of each part in the furnace, the conventional fluidized bed incinerator is The following problems were found. In other words, the secondary combustion air blown out from the first nozzle presses the flow of the combustion gas against the wall surface on the side opposite to the side where the first nozzle is provided, and as a result, the combustion gas and the secondary combustion air flow. Even if air rises as a laminar flow and the secondary combustion gas is blown out of the second nozzle at the throttle portion, the second nozzle is provided so as to face each other. The flow of the combustion gas and the secondary combustion air that have flowed in is separated by the secondary combustion air blown out from the second nozzle, but rises as a laminar flow, whereby the combustion gas and the secondary combustion air flow. Mixing with working air becomes difficult. Therefore, many unburned components contained in the combustion gas are discharged without completely burning, and highly toxic dioxins are generated in the combustion exhaust gas by the dioxin precursor contained in the unburned components. . The dioxins are collected by the bag filter type dust collector together with other dust, but are not perfect, and it is desired to reduce the amount of generated dioxins due to the problem of post-treatment of collected ash.
[0005]
Furthermore, recently, in order to reduce the combustion fluctuation by reducing the burning speed of the incinerated material and reduce the unburned portion, the incinerated material inlet in the fluidized bed formed at the bottom of the primary combustion chamber. It is considered that the side portion is a heating zone for drying and pyrolysis, and the remaining portion is a combustion zone for undecomposed residue and char sent from the heating zone. In such a fluidized bed incinerator, steam and pyrolysis gas are generated from the heating zone and combustion gas is generated from the combustion zone. In this case, the steam and pyrolysis gas, the combustion gas, and the first The drift with the secondary combustion air blown out from the nozzle becomes remarkable, making it more difficult to mix them.In the secondary combustion chamber, many unburned components contained in the combustion gas are completely burned. Therefore, highly toxic dioxins are generated in the combustion exhaust gas by the dioxin precursor contained in the unburned matter. The dioxins are collected by the bag filter type dust collector together with other dust, but are not perfect, and it is desired to reduce the amount of generated dioxins due to the problem of post-treatment of collected ash.
[0006]
An object of the present invention is to solve the above problems and to provide a fluidized bed incinerator capable of suppressing the remaining of unburned matters when incinerating municipal waste, industrial waste, and the like.
[0007]
Means for Solving the Problems and Effects of the Invention
In the fluidized bed incinerator according to the present invention, a primary combustion chamber is provided at a lower portion of the furnace main body, a secondary combustion chamber is provided at the upper portion thereof, and a throttle portion is provided between the primary combustion chamber and the secondary combustion chamber, In a fluidized bed incinerator in which a fluidized bed is formed in a primary combustion chamber, the horizontal cross-sectional shape of the primary combustion chamber is rectangular, and one of two opposite walls of the primary combustion chamber is Nozzles for blowing air for secondary combustion into the primary combustion chamber are provided at the central part in the longitudinal direction at the upper part and at the central part and both ends in the longitudinal direction at the upper part of the other wall, respectively, and the primary combustion chamber is provided. The size of the tip outlet of the nozzle on the one wall is larger than the tip outlet of the nozzle at the central portion in the longitudinal direction on the other wall of the primary combustion chamber, and The cross-sectional shape is square, and the opposed sides of the secondary combustion chamber A plurality of nozzles for blowing secondary combustion air into the secondary combustion chamber are provided below the two walls, respectively, and the air of the nozzle provided on one of the two walls of the secondary combustion chamber is provided. There is provided a means for alternately switching the blowing amount and the air blowing amount of the nozzle provided on the other wall so that one is large and the other is small .
[0008]
According to the fluidized bed incinerator of the present invention, the horizontal cross-sectional shape of the primary combustion chamber is rectangular, and the longitudinal direction of the upper part of one of the two opposing walls of the primary combustion chamber is measured in the longitudinal direction. A nozzle for blowing air for secondary combustion into the primary combustion chamber is provided at the central portion and at the central portion and both ends in the longitudinal direction at the top of the other wall, respectively. Since the size of the tip outlet of the nozzle is larger than that of the nozzle at the center in the longitudinal direction on the other wall of the primary combustion chamber, the secondary combustion air is blown from all the nozzles. When discharged, the secondary combustion air blown out from the nozzle on the one wall becomes a thick flow, travels to the other wall side, and is blown out from the nozzle at the center in the longitudinal direction of the other wall. Divided by a small stream of secondary combustion air Toward both ends in the length direction of the other wall. Next, the air is advanced toward the one wall by the secondary combustion air blown out from the nozzles at both ends in the longitudinal direction of the other wall. Therefore, in combination with the fact that the horizontal cross section of the primary combustion chamber is rectangular, two large swirls are formed in the primary combustion chamber, and the combustion gas and the secondary combustion air rising from the fluidized bed are separated. The stirring and mixing can be performed efficiently, and a part of the unburned portion in the combustion gas can be burned. When the fluidized bed is divided into a heating zone and a combustion zone, the steam and the pyrolysis gas rising from the heating zone, the combustion gas rising from the combustion zone, and the secondary combustion air are separated from each other. The stirring and mixing can be performed efficiently, and a part of the pyrolysis gas and a part of the unburned portion in the combustion gas can be burned. In any case, the unburned portion is further combusted in the throttle section and the secondary combustion chamber following the primary combustion chamber, and as a result, the unburned portion containing the dioxin precursor is reduced as compared with the conventional fluidized bed incinerator. The amount of dioxins is reduced, and the generation of dioxins is prevented.
[0009]
Further, the horizontal cross section of the secondary combustion chamber has a rectangular shape, and a plurality of nozzles for blowing secondary combustion air into the secondary combustion chamber are provided below two opposing walls of the secondary combustion chamber. The amount of air blown from a nozzle provided on one of the two walls of the secondary combustion chamber and the amount of air blown from a nozzle provided on the other wall of the secondary combustion chamber are such that one is large and the other is large. Since it is provided with means for alternately switching to be small, the collision position of the secondary combustion air blown out from the nozzle provided on the one wall and the nozzle provided on the other wall changes. As a result, the flow of the combustion gas and the secondary combustion air flowing into the secondary combustion chamber from the throttle portion, or the flow of the steam, the pyrolysis gas, the combustion gas, and the secondary combustion air is further disturbed, and these agitation is caused. Mixing and these with the nozzle of the secondary combustion chamber Stirring and mixing with out secondary combustion air is promoted. Therefore, the remaining portion of the pyrolysis gas and the remaining portion of the unburned portion in the combustion gas can be burned, and the final unburned portion is drastically reduced .
[0010]
In the fluidized bed incinerator according to the present invention, the horizontal cross-sectional shape of the throttle is rectangular, and a plurality of nozzles for blowing secondary combustion air into the throttle are provided on two opposing walls of the throttle. It is preferable that all the nozzles are provided so as to be staggered as a whole when viewed from a plane. In this case, when the secondary combustion air is blown out from all the nozzles provided in the throttle section, the flow of the combustion gas and the secondary combustion air flowing into the throttle section from the primary combustion chamber, or steam, pyrolysis gas In addition, the flow of the combustion gas and the secondary combustion air is further disturbed, and the agitation and mixing of these and the agitation and mixing of these with the secondary combustion air blown out from the nozzle of the throttle portion are promoted, and the pyrolysis gas is also removed. A part and a part of the unburned portion in the combustion gas can be burned. Therefore, the final amount of unburned matter further decreases .
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0012]
1 to 4, the fluidized bed incinerator has a primary combustion chamber (2) provided at a lower portion of a furnace body (1), and a secondary combustion chamber (3) provided at an upper portion thereof. ) And the secondary combustion chamber (3) are provided with a throttle (4).
[0013]
The primary combustion chamber (2) has a horizontal cross-sectional square shape, and an incinerated material inlet () for feeding municipal solid waste, industrial waste, etc. into the primary combustion chamber (2) at an intermediate portion of the height of the front wall (2a). 5) is formed. A fluidized bed (6) is formed at the bottom of the primary combustion chamber (2). The front of the fluidized bed (6) is provided with a heating zone (7) for drying and thermally decomposing the incinerated material sent from the incinerated material introduction port (5) by heating, and also for the fluidized bed (6). The rear part is a combustion zone (8) for burning a mixture of undecomposed residue and char sent from the heating zone (7). In the heating zone (7) of the fluidized bed (6), a plurality of diffuser tubes (11) arranged on an inclined wall (9) inclined downward toward the rear in the first half of the bottom wall of the primary combustion chamber (2). ), A fluidized bed is formed using a fluid medium such as sand. In the combustion zone (8) of the fluidized bed (6), it is formed in the latter half of the bottom wall of the primary combustion chamber (2) and is located above an outlet (12) for discharging ash, incombustibles and a part of the fluidized medium. A fluidized bed is formed by a plurality of diffuser tubes (13) arranged using a fluid medium such as sand. The fluid medium circulates between the zones (7) and (8). The primary combustion air is supplied to the air diffusers (11) and (13) of both zones (7) and (8). The supply amount of the primary combustion air to both diffuser tubes (11) and (13) is such that a fluidized bed of a predetermined height is formed in the fluidized bed (6) by the fluidized medium, and the two zones ( 7) The amount is set such that the temperature of (8) is maintained at a predetermined temperature. The temperature of both zones (7) and (8) of the fluidized bed (6) depends on the size of the furnace and the quality of the incinerated material, but if the incinerated material is flammable, for example, containing a large amount of paper or plastic, In order to prevent unstable combustion due to instantaneous decomposition or combustion, the temperatures of both zones (7) and (8) are maintained at 550 to 650 ° C.
[0014]
Inside the primary combustion chamber (2), at the center in the left-right direction at the upper end of the rear wall (2b) of the primary combustion chamber (2), and at the center in the left-right direction and at both left and right ends at the upper end of the front wall (2a). Is provided with a nozzle (14) (hereinafter, referred to as a first nozzle) for blowing out secondary combustion air. The size of the front end outlet of the first nozzle (14) on the rear wall (2b) is larger than the front end outlet of the first nozzle (14) at the center in the left-right direction on the front wall (2a). Air is supplied to the first nozzle (14) of the front wall (2a) through a pipe (16) branched from a pipe (15) for supplying air for primary combustion to both air diffusers (11) and (13). Air is supplied to the first nozzle (14) of the rear wall (2b) through a dedicated first nozzle pipe (17).
[0015]
The horizontal cross-sectional shape of the throttle portion (4) is a rectangular shape that is long in the left-right direction, the length in the left-right direction is equal to the length in the left-right direction of the primary combustion chamber (2), and only the width in the front-rear direction is the primary combustion chamber ( It is smaller than the length in the front-back direction of 2). A plurality of nozzles (18) (hereinafter, referred to as second nozzles) for blowing secondary combustion air into the throttle section (4) are provided on both front and rear walls (4a) and (4b) of the throttle section (4), respectively. They are provided at intervals in the left-right direction. All the second nozzles (18) are provided so as to be staggered as a whole when viewed from a plane. That is, the second nozzle (18) of the front wall (4a) is one less than the second nozzle (18) of the rear wall (4b), and is adjacent to the rear wall (4b) in the left-right direction. The second nozzles (18) are arranged so as to be located in the middle of each other. All the second nozzles (18) branch off from a first nozzle pipe (17) that supplies air for secondary combustion to the first nozzle (14) on the rear wall (2b) of the primary combustion chamber (2). The secondary combustion air is supplied by the second nozzle pipe (21) that extends.
[0016]
The secondary combustion chamber (3) has a square horizontal cross section, and the size of the horizontal cross section is equal to the size of the horizontal cross section of the primary combustion chamber (2). At the lower ends of the front and rear walls (3a) and (3b) of the front and rear walls of the secondary combustion chamber (3), a plurality of nozzles (22) (hereinafter, referred to as blowout) for blowing secondary combustion air into the secondary combustion chamber (3), respectively. 3rd nozzles) are provided at intervals in the left-right direction. The third nozzle (22) of the front wall (3a) and the third nozzle (22) of the rear wall (3b) face each other. All the third nozzles (22) have the third nozzles branching and extending from the second nozzle pipe (21) for supplying the secondary combustion air to the second nozzles (18) of the throttle section (4). The secondary combustion air is supplied by the supply pipe (23).
[0017]
The third nozzle pipe (23) branches back and forth in the middle, and the front and rear branch portions (23a) (23b) have the same number of third nozzles (22) as the front and rear walls (3a) (3b). It branches and is connected to the third nozzle (22). At the part where the third nozzle pipe (23) branches forward and backward, the air blowing amount of the third nozzle (22) of the front wall (3a) and the air of the third nozzle (22) of the rear wall (3b) are provided. An air blowing amount switching device (24) (switching means) for alternately switching the blowing amount so that one is large and the other is small is provided. The switching device (24) has a casing (26) in which air outlets (25) are formed at both left and right ends, and has an axis arranged in the casing (26) and extending in the front-rear direction and rotating around the axis. A freely adjusting hollow cylindrical blowing amount adjusting member (27) having both ends closed. Branch portions (23a) (23b) are connected to both air outlets (25) of the casing (26), respectively. A motor (28) is mounted on the outer surface of the left side wall of the casing (26), and the blowout amount adjusting member (27) is rotated by the motor (28). A third nozzle pipe (23) is connected to a right end wall of the blowout amount adjusting member (27) via a rotary joint (29). In addition, two large and small air outlets (31) and (32) are formed on the peripheral wall of the blow-out amount adjusting member (27) on one diameter. Then, when the large air outlet (31) of the blowout amount adjusting member (27) faces rearward and the small air outlet (32) faces forward, the air blowing of the third nozzle (22) of the rear wall (3b) is performed. The amount is large, and the amount of air blown from the third nozzle (22) of the front wall (3a) is small. Further, when the blow-off amount adjusting member (27) is rotated by the motor (28) so that the large air outlet (31) faces forward and the small air outlet (32) faces rearward, the front wall (3a) is closed. The air blowing amount of the third nozzle (22) is large, and the air blowing amount of the third nozzle (22) of the rear wall (3b) is small. In this manner, when the direction of the air outlets (31) and (32) is changed by rotating the blow-out amount adjusting member (27) at predetermined time intervals by the motor (28), as shown in FIG. The amount of air blown from the third nozzle (22) and the amount of air blown from the third nozzle (22) on the rear wall (3b) are alternately switched so that one is large and the other is small. The collision position between the air blown from the third nozzle (22) of (3a) and the air blown from the third nozzle (22) of the rear wall (3b) changes.
[0018]
The supply amount of the secondary combustion air to the first to third nozzles (14) (18) (22), an outlet temperature of 850 to 950 ° C. in the secondary combustion chamber (3), O ₂ content of 6 Adjusted to be 9%.
[0019]
In the fluidized bed incinerator having the above configuration, the material to be incinerated is fed from the inlet (5) to the heating zone (7) of the fluidized bed (6) of the primary combustion chamber (2). In the heating zone (7), a fluidized bed is formed by a diffuser pipe (11) using a high-temperature fluidized medium returned from the combustion zone (8), and the incinerated material that has been sent is heated and dried. At the same time, the plastic therein is thermally decomposed. The pyrolysis gas and steam rise in the primary combustion chamber (2).
[0020]
The mixture of the undecomposed residue and char generated in the heating zone (7) is sent to the combustion zone (8) together with the fluidized medium, and is burned in the fluidized bed formed by the diffuser (13). The combustion gas rises in the primary combustion chamber (2). Part of the ash, incombustibles and fluidized medium is discharged from the outlet (12) to the outside of the furnace body (1), and only the fluidized medium is separated and returned to the fluidized bed (6) in the primary combustion chamber (2). It is.
[0021]
When the secondary combustion air is blown out from all the first nozzles (14), the secondary combustion air blown out from the first nozzles (14) on the rear wall (2b) flows forward as a thick flow. The left and right side walls (2c) and (2d) of the primary combustion chamber (2) are divided into two parts by the small flow of the secondary combustion air blown out from the first nozzle (14) in the left-right central part of the front wall. Head to the side. Next, the air is advanced toward the rear wall (2b) by the secondary combustion air blown out from the first nozzles (14) at the left and right ends of the front wall (2a). Therefore, two large vortices are formed in the upper part in the primary combustion chamber (2), and the steam, the pyrolysis gas and the combustion gas that have risen from the fluidized bed (6), and the two vortices blown out from the first nozzle (14). The air for the next combustion is efficiently stirred and mixed, and a part of the pyrolysis gas and a part of the unburned portion in the combustion gas burn.
[0022]
The remainder of the steam, the pyrolysis gas, the combustion gas, and the balance of the secondary combustion air further rise and enter the throttle section (4), and are discharged from all the second nozzles (18) provided in the throttle section (4). When the secondary combustion air is blown out, the flow of the steam, the remainder of the pyrolysis gas, the combustion gas and the remainder of the secondary combustion air flowing into the throttle section (4) from the primary combustion chamber (2) is further disturbed. This promotes the stirring and mixing of these, and the stirring and mixing of these with the secondary combustion air blown out from the second nozzle (18), as well as a part of the pyrolysis gas and a part of the unburned part in the combustion gas Burns.
[0023]
The remainder of the steam, the pyrolysis gas, the combustion gas, and the balance of the secondary combustion air further rise and enter the secondary combustion chamber (3). Here, while rotating the blow-out amount adjusting member (27) by a motor (28) every predetermined time and changing the direction of the blow-out ports (31) and (32), the secondary combustion When air is blown, the amount of air blown from the third nozzle (22) on the front wall (3a) and the amount of air blown from the third nozzle (22) on the rear wall (3b) are determined to be large on one side and small on the other. The collision position between the air blown from the third nozzle (22) on the front wall (3a) and the air blown from the third nozzle (22) on the rear wall (3b) Changes. As a result, the flow of the steam, the remainder of the pyrolysis gas, and the remainder of the combustion gas and the air for the secondary combustion flowing into the secondary combustion chamber (3) from the throttle section (4) is further disturbed, and the mixing and stirring of these flows is performed. Further, these are sufficiently stirred and mixed with the secondary combustion air blown out from the third nozzle (22). Therefore, the remainder of the pyrolysis gas and the remaining unburned portion in the combustion gas burn. In this way, complete combustion is promoted, the unburned components in the combustion gas containing the dioxin precursor are drastically reduced, and the generation of dioxin is prevented beforehand, and an exhaust gas with a very small or no dioxin content is released into the atmosphere. You.
[0024]
In the above embodiment, the fluidized bed is divided into the heating zone and the combustion zone. However, the present invention is not limited to this, and the fluidized bed does not necessarily need to be divided into the heating zone and the combustion zone.
[Brief description of the drawings]
FIG. 1 is a vertical sectional view showing one embodiment of a fluidized bed incinerator according to the present invention.
FIG. 2 is an enlarged sectional view taken along line II-II of FIG.
FIG. 3 is an enlarged sectional view taken along line III-III of FIG. 1;
FIG. 4 is an enlarged sectional view taken along line IV-IV of FIG. 1;
FIG. 5 is a graph showing a change in an amount of air blown from a third nozzle before and after a secondary combustion chamber.
[Explanation of symbols]
(1): Furnace body
(2): Primary combustion chamber
(2a): Front wall
(2b): Rear wall
(3): Secondary combustion chamber
(4): Aperture section
(6): Fluidized bed
(14): No. 1 nozzle
(22) : No. 3 nozzle
(24) : Air blowing amount switching device (switching means)

Claims (2)

A primary combustion chamber is provided at a lower portion of the furnace main body, a secondary combustion chamber is provided at an upper portion thereof, a throttle portion is provided between the primary combustion chamber and the secondary combustion chamber, and a fluidized bed is formed in the primary combustion chamber. Fluidized bed incinerator,
The horizontal cross-sectional shape of the primary combustion chamber is rectangular, and a central portion in the longitudinal direction at the top of one of the two opposing walls of the primary combustion chamber and the length at the top of the other wall. in the central portion and both end portions of the direction the nozzle for blowing secondary combustion air into the primary combustion chamber respectively are provided, the size of the tip outlet of the nozzle of said one wall of the primary combustion chamber, the primary combustion The other end wall of the chamber is made larger than the tip outlet of the nozzle at the center in the longitudinal direction ,
The horizontal cross section of the secondary combustion chamber has a rectangular shape, and a plurality of nozzles for blowing secondary combustion air into the secondary combustion chamber are provided below two opposing walls of the secondary combustion chamber, respectively. The amount of air blown from the nozzle provided on one of the two walls of the secondary combustion chamber and the amount of air blown from the nozzle provided on the other wall are one large and the other small. A fluidized bed incinerator provided with means for alternately switching the incinerator. The horizontal cross-sectional shape of the throttle portion is rectangular, and a plurality of nozzles for blowing secondary combustion air into the throttle portion are provided on two opposing walls of the throttle portion, respectively. 2. The fluidized bed incinerator according to claim 1, wherein the fluidized bed incinerator is provided in a staggered arrangement as viewed from above.

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